Micelle kinetics rearrangement

Fig. 4.12 Micelle kinetics mechanisms 1- formation-dissolution, 2 - rearrangement, 3 aggregation-disintegration...

The above picture shows that to describe the kinetics of adsorption, one must take into account the diffusion of monomers and micelles as well as the kinetics of micelle formation and dissolution. Several processes may take place and these are represented schematically in Fig. 4.9. Three main mechanisms may be considered, namely formation-dissolution (Fig. 4.9 (a)), rearrangement (Fig. 4.9 (b)) and stepwise aggregation-dissolution (Fig. 4.9 (c)). To describe the effect of micelles on adsorption kinetics, one should know several parameters such as micelle aggregation number and rate constants of micelle kinetics [25]. 

The complex dielectric spectra of water/ChEOjo and water/ChEOi binary systems (at 5, 10, and 15 wt% water) were determined at 25 °C by time-domain reflectom-etry (frequency range of 0.1-20 GHz, [39]). The low-frequency process was assigned to the kinetics of the hydrophiUc layer of micelles, including the motion of hydrated oxyethylene chain and hydrated water. Additionally, the relaxation time of the high-frequency process was attributed to the cooperative rearrangement of the H-bond network of bulk water. Following various calculations, which are reported in the article, the effective hydration number of ethylene chain Zeo was estimated. 

One of the rare works on the kinetics of the formation of mixed micelles of Pluronics and surfactants also treats the system L64/SDS [58]. In temperature-jump experiments, the authors identified three different relaxation times for the L64/SDS mixture. The fastest ps) is associated with the binding of additional L64 unimers to the micelles. The two slower relaxation processes are interpreted as structural rearrangement of the mixed micelles and micelle clustering. These findings are qualitatively in agreement with the first kinetic investigation of these mixtures by Hecht and Hoffmann [59]. 

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